Steam-boiler



(No Model.)

D. T. LAWSON.

STEAM BOILER.

No. 407,538. Patented July 23, 1889.

WITNESSES: INVENTOR:

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UNITED STATES PATENT OFFICE.

DANIEL T. LAWSON, OF WELLSVILLE, OHIO.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 407,538, dated July 23, 1889. Application filed February 13, 1889. Serial No. 299,787. (No model.)

To all whom it may concern.-

Be it known that I, DANIEL T. LAWSON, of \Vellsville, in the county of Oolumbiana and State of Ohio, have invented a new and useful Improvement in Steam-Boilers, of which the following is a specification.

My invention comprehends certain improvements upon the steam-boiler patented by me April 27, 1880, No. 227,024. In that patent I described and claimed a process of preventing steam-boiler explosions by retarding or prolonging the flow of steam from the waterspace to the steam-space by means of a diaphragm or partition having a valved openin g of less size than the outlet from the steamspace, whereby the sudden conversion of water into steam (due to the abstraction of steam from the steam-space) is prevented and its concussive effect upon the boiler is avoided. In accordance with my theory as expressed in that patent and subsequently confirmed by the report of United States engineers upon the subject it has been demonstrated that steam-boiler explosions are mainly due to a sudden reduction of steam-pressure and the immediate conversion of hot waterinto steam with explosive energy, which, having no relief, bursts the boiler. The causes which produce this sudden reduction of steam-pressure upon the water are, first, the sudden opening of the throttle-valve and rush of steam into the cylinder, being instantly followed by the closure of the steam-port, as in starting the engine, and, secondly, the injection of cold water into the steam-space in starting the feedpumps, which causes an instantaneous condensation of steam, this being liable to occur when the inlet end of the feed-water pipe terminates too high in the boiler, or when the feed-pipe is uncovered by the lowering of the water in the boiler by the careening of the boiler on shipboard. It will thus appear that a risk of explosion is always involved when steam is allowed to escape from the boiler and its escape suddenly arrested, or the pressure upon the heated water in the boiler is suddenly reduced Without adequate vent to carry off the ooncussive strain produced by the bursting of the heretofore quiescent hot water into steam.

In the patent before referred to I employed a slide-valve attached to a stem and extend ing through the shell of the boiler, which valve could be adjusted at will over the opening in the diaphragm separating the steam from the water space. As the adjustment of the size of this opening to the escape of steam required nice judgment on the part of the-engineer, only the most expert engineers could make available the full advantages of my invention, while the other class of unskilled engineers are the very ones who need it most.

My present invention is intended to render the boiler automatic in its action in accordance with my theory, so that all may profit by its advantages without the exercise of judgment, and whereby also the firing-surface of the boiler is rendered free from incrustation' and self-cleaning to a certain extent. Figure 1 is a side elevation of the boiler witha portion of the shell and also a portion of the diaphragm broken away to show the internal construction, and Fig. 2 a transverse section of my improved boiler.

A is the shell of the boiler.

B is the horizontal diaphragm, running lengthwise the boiler and separating the water-space G from the steam-space O. This boiler may be of any desired size or shape, and may be provided with return-fines or firetubes.

In the diaphragm B are formed several openings a, and over each of these openings is arranged a check-valve 1), opening upwardly and held down by a weight or spring. The aggregate size of these openings is considerably less than the size of the steam-outlet 0 from the steam-space, so that steam will pass from the lower space 0 to the upper space C somewhat slower than it will escape from the upper space through the steam-outlet, so that no matter how impulsive or intermittent the escape of steam from the steam-space may be the passage of the steam from the lower space 0 to the upper space 0' is more or less constant or prolonged through a greater space of time, thus avoiding a sudden removal of press ure from the water and the resultant concussive strain. These automatic valves open whenever the steam-pressure is reduced by' discharge from the upper space 0, and they serve another very important function, which I will now proceed to explain.

I have found in the operation of my boiler that all the sedimentary matters which produce scale or inerustation are thrown up on the diaphragm, and if they can be held there and eliminated before they are allowed to wash back into the water-compartment. by overflow of the diaphragm (which may under certain conditions occur, and cause them to settle upon the bottom plates and fines, where they may be burn ed into adherence to the iron) my boiler can be made self-cleanin g and free from scale. Ordinarily, when the boiler is in action, the sedimentary matters when first eliminated do not adhere to the boiler; but when the boiler is at rest they settle down upon the fire-surface of the boiler, and when the boiler is fired up they become burned into an adhering incrustation, which in a short time seriously interferes with the steaming capacity of the boiler, involving a great waste of fuel, as well as injury to the iron. \Vith my diaphragm these sedimentary matters pass to the upper side of the diaphragm when the boiler is in action, and are there retained by the automatic check-valves on a surface out of contact with the fire, where they cannot become incrusted, but may be blown oif in the form of a slush or semi-fluid mass. To facilitate this action, the diaphragm is formed with trough-like grooves e e on its opposite sides, and at the lower ends of these troughs there are blow-off pipes ff, by which the troughs maybe cleaned of their lead of impurities. By this means the firingsurface of the boiler as well as fines is always kept clean and free from incrustation and capable of a maximum steaming effect.

In connection with the valved openings in the diaphragm, Imay use a number of small holes h through the diaphragm of about a quarter of an inch in diameter, which act in conjunction with the valved openings, but which always remain open and effect the liberation of perfectly dry steam. These openings should, however, be computed in with the valved openings in determining the aggregate area of the openings in the diaphragm, which should always be kept considerably below the area of the discharge-openings from the steam-space.

Having thus described my invention, what I claim as new is- 1. A steam-boiler having its steam-space separated from the water-space bya horizontal diaphragm provided with openings in the same, and combined with upwardly-opening check-Valves arranged upon the diaphragm, substantially and for the purpose described.

2. The combination, with a steam-boiler,0f a horizontal diaphragm separating the steam space from the water-space and provided with upwardly-opening check-valves and gathering-troughs for sediment, and blow-out pipes extending through the boiler from the level of the troughs, substantially as and for the purpose described.

DANIEL T. LAWVSON.

Witnesses:

A. B. JENKINS, A. G. SMITH. 

